This chapter explores the development of spontaneous dialectic in ancient Greece, tracing its tranformation from early cosmological inquiries to a refined method of dialogue and argumentation. It begins with the shift from myth to logos, tracing how pre-Socratic philosophers sought the primary substance (arche) of the cosmos. Heraclitus occupies a central position in this transformation, introducing the notion of a dynamic, ever-changing cosmos and laying the foundations for the dialectical mode of thought. The chapter highlights a crucial shift from these cosmological inquiries to a focus on the role of the human subject in the construction of knowledge, an approach advanced by the Sophists and Socrates. Plato elevated dialectic to a supreme methodological status, conceptualising it as the ‘kingly art’ of philosophical investigation. Aristotle, departing from Plato’s perspective, reimagined dialectic as a method for critically examining received ‘accepted opinions’ (‘endoxa’). The chapter concludes by exploring how the decline of the Platonic and Aristotelian systematic philosophies led the Hellenistic schools—including Stoicism, Epicureanism, and Skepticism—to reconceptualise dialectic according to their distinctive philosophical priorities. Finally, the chapter demonstrates the crucial role of Neoplatonism in facilitating the transition from ancient philosophy to medieval theology.